Method and apparatus for prevention of formations in transfer lines



Feb. 3, 1942. F. R. RUSSELL 2,271,955

METHOD AND APPARATUS FOR PREVENTION OF FORMATIONS IN TRANSFER LINES Filed June 17, 1959 2 Sheets-Sheet 1 Feb. 3, 1942. F. R. RUSSELL METHOD AND APPARATUS FOR PREVENTION OF FORMATIONS IN TRANSFER LINES ed June 17, 1939 2 Sheets-Sheet 2 Patented Feb. 3, 1942 1 UNITED STATE METHOD AND APPARATUS FOR PREVEN- TION F qFORMATIONS 1N TRANSFER- LINES Francis R. Russell,Eliz abeth,- N. J., assignor to Standard Oil DevelopmentCompany, a corporation of Delaware Application June 17, 1939, Serial No. 279,636 6 Claims. (01.196-47) The present invention relates to the preverrtion of formationsin transfer lines and the like.

The invention is directed to the reduction and I elimination of deleterious coke and tar formations in petroleum oil transfer lines,heating tubes, and reaction vessels. :The invention comprises processing oils in a metallic vessel concentrically disposed within a hydrogen filled metallic jacket. The invention further comprises a hydrogenfilled jacket surrounding any or all of the tubes and vessels containing the reaction products whichfor any reason are subject to the deposition of coke or tarry materials upon their surfaces. The invention is particularly directed to transferring, heating or reacting petroleum hydrocarbons in concentrically disposed lines or in concentrically disposed "re-' action vessels inwhioh hydrogen gas is maintained in an area segregated from said petroleum hydrocarbons. The concentrically disposed tubes or vessels comprise a hydrogen permeable metallic vessel disposed preferably within a hydrogenfilled copper-lined metallic jacket.

- The present invention is particularly applica-.

ble in processes in which petroleum oils are'subjected to elevated temperatures and pressures, as for example,in the; conversion of petroleum oils into relatively higher boiling and into relatively lower boiling stocks. In these oil cracking processes, the feedmaterial is subjected to various temperature and pressure conditions for various time periods which are usually measured in terms "of yield per unit throughput, hereinafter termed conversion per pass. These vari-'- ous variable factors'are optimumly adjusted and,

to a large extent, are functions of the particular feed material being processed and upon the yields and quality of the products desired. It has been a normal cracking operation.

respective tubes or' vessels under sufiicientpressureto cause the air or oxygen to permeate through the porous wall of the inner tube or vessel. The gas thusmay form substantially a gas wall between the liquid' being treated and the wall of the inner tube or vessel, or may serve to oxidize any coke which forms. Processes of this character have not been entirely successful due to the inherent difficulties in the manufacture of. satisfactory air and oxygen permeable porous tubes or vessels having necessary strengths and wearing qualities. v I have now discovered a process and apparatus for carrying it out by which these difficulties are overcome, resulting in-improved operating efficiencies and greater yields of higher quality products. The process of my invention may be readilyunderstood by'reference to the attached drawings illustrating one modification of the same. 'For purposes of illustration I have applied my invention to a conventional petroleum oil cracking unit. I 1

Figure 1 shows a diagrammatic'fiow plan of Figure 2 is a sketch illustrating a, suitable tube construction in accordancewith my invention, while Figure 3 illustrates a reaction chamber or soaking drum constructed in accordance with the present invention; I

Referring specifically to Figure 1, it is assumedthat the feed oil is a petroleum gas oil fraction boilingin the range from about 400 F. to 700 F. The'fresh feed oil is introduced by means of feedline I into the bottom of primary bubble tower 2. The feed, together with cycle oil, is withdrawn from the bottom of primary bubble tower 2 and introduced into furnace 4 by means of line found that the capacity, yields and operating.

conditions of petroleum oil cracking operations are limited by the tendency of the oil being treated to form deleterious 'coke and tarry formations. The formation of the coke and tar usu-- ally occurs upon the surfaces of the reaction chambers and in the tubes in which the oil is heated to the desired temperatures, as well as in the tubes carrying the oil through the cracking unit. Various processesand equipment havebeen employed in an effort to eliminate and reduce coke formations.

within a steel outer tube or vessel and that air A I For instance, it has been suggested that the oil being treated be' vapors pass or oxygen be maintained in the area between the 5s 3. Furnace 4 is designed to secure optimum heat transfer as the feed stock flows through tubes 5 in the respective sections and to bring the oil up to the desired temperatures. The totalfeed is withdrawn from furnace 4 by means of line 6 and passed into soaking drum or reaction chamber 1 in which the oil is held for an additional time under .crackingconditions. The cracked" oil is withdrawn from reaction drum 1 by means of line 8 and passed through pressure release valve 9 into evaporator Ill. The flashed overhead from evaporator Ill through line lLinto primary bubble tower 2, while tar or fuel oil of the desired ravity is removed as a bottoms from evaporator 10 by means of line 22. Cycle stock accumulates in the bottom of primary bubble tower 2, while vapors pass overhead by'means of line l2 into secondary bubble tower I3. The temperature at the top of tower I3 is controlled so as to produce an overhead distillate of the desired end point which is removed by line l4 and condensed in cooler l5. Fixed gas and uncondensed hydrocarbon vapors are separated from the condensate in distillate drum l6 and removed by means of line I1, while the condensed distillate is removed by means of line 18. Heating oil may be withdrawn from the bottom of tower l3 by means of line l9 and may be recycled, if desired, through line or withdrawn by means of line 2|.

Figure 2 illustrates in detail the tubes or transfer lines of the present invention as applied to tubes and lines 3, 5, 6, and 8 of Figure 1. It is to be assumed that any number of tubes may be employed and arranged in any desirable manner.

All of the tubes, vessels, and transfer lines may be of the type of the invention. In general, however, the tubes, vessels, and transfer lines of the present invention are employed only where coking difliculties are critical. The tube of the present invention as illustrated in detail in Figure 2 comprises a hydrogen permeable main tube 36 and a concentrically disposed jacket tube 3|. Jacket tube 32 preferably comprises a copper tube or a copper-lined steel tube. Tube preferably comprises a copper and aluminumfree metallic tube, preferably a steel tube. Suitable means are employed for maintaining hydrogen at any desirable pressure in the area between the jacket tube 3! and the main tube 3!]. Hydrogen is injected into this area by means of hydrogen inlets 32 and 33. The area between tubes 39 and 3! may be divided into numerous sections. As illustrated in Figure 2, the area between the respective tubes is divided into sections 34 and 35 by means of baiiie 36. drogen pressure may be adjusted in the respective areas to give the necessary or desirable rate of hydrogen penetration. The hydrogen within these areas is held under suiiicient pressure to cause the hydrogen to permeate through the hydrogen permeable metallic tube 363 into the oil being processed. If desired, heating may be secured by direct combustion by the introduction of air or nitrogen-containing gas into tube 30 by means of line 31.

Figure 3 illustrates in detail a reaction chamber or soaking drum constructed in accordance with the present invention. This chamber comprises a jacket vessel t5] and a main hydrogen permeable vessel H. The oil being processed is introduced into reaction vessel M by means of line 42 and withdrawn by means of line 43. The

inner reaction vessel 4H comprises preferably a copper and aluminum-free metallic vessel and is preferably a steel vessel. Outer vessel Ml comprises a metallic vessel, preferably a copperlined, steel vessel. Means 44 and d5 are provided for introducing hydrogen at the desired pressure into the area between the vessels 4G and M. The area between vessels 4B and 4! may be subdivided into various sections. As illustrated, the area between the vessels is divided into areas 47 and 48 by means of bafile 3E. The hydrogen pressure may be adjusted in the respective areas to give the necessary or desirable rate of hydrogen penetration through the wall of vessel 4| in each subdivision.

The process of the present invention may be widely modified. It is to be understood that it The hymay readily be applied to processes other than petroleum oil cracking operations.

The pressure maintained on the hydrogen within the area between the respective concentric lines or vessels will vary Widely and will be a function of temperature, the wall thickness of the inner metallic vessel, the pressure of the oil within said vessel, and the amount of hydrogen desired to permeate into the oil within said vessel.

In general, when using inner steel vessels having a wall thickness of from three-eights to five-eighths inches, it is preferred to maintain the hydrogen at a pressure of from one to ten atmospheres above the pressure of the material in the inner tube. However, if only a relatively small amount of hydrogen is desired to permeate into the inner tube, the hydrogen pressure may be equivalent to, or even somewhat lower than the pressure within the inner tube.

The outer jacket is preferably a cupreous-lined steel tube or vessel. However, other metals having the property of being impermeable to hydrogen may be used, as for example, aluminum. The cupreous lining may be of relatively small thickness, as for example, one-sixteenth to oneeighth inch. The thickness of the copper-lined jacket steel tube or vessel is suiiicient to safely withstand operating conditions and pressures. For the sake of economy, the elimination of the copper lining in certain operations might be permissible.

In order to illustrate the present invention, the following data are given which should not be construed as limiting the same in any manner whatsoever: I

Example 1 The following dataclearly illustrate the advantage of the applicants invention with respect to the control of the permeation of hydrogen:

Hydrogen in ccs. per square centimeter per secand for 1 mm. thickness at, 1 atmosphere of Petroleum oil when passed under cracking conditions through steel heating tubes, transfer lines, and reaction chambers of 0.5 inch in thickness, said tubes, transfer lines and reaction chambers being jacketed with cupreous lined steel tubes will absorb the following amount of hydrogen from the area between the respective vessels under the following conditions:

Hydroigen cc./I.uiu./ o Dilferential Inner steel Surface Temp" pressure wall thick. 1

' To oil To atmos.

Atmosphere LOUDO C 1 .5 4.40 500: C 1 5 0. 44 0 500 C 5U. 5 3.,10

The process of the, present invention is not to be limited by any theory or mode of. operat on, but only by the following, claims in which substantial it is desired to claim all novelty in so far as the prior art permits. I a

I claim:

1. A process for maintaining hydrocarbons perforate hydrogen-permeable wall, supplying heat to the hydrocarbons, and maintaining hydrogen under sufficient pressure in an outer zone spaced from the inner zone by said wall to cause flow of hydrogen through said hydrogen-permeable wall of said inner zone into the hydrocarbons passing through said inner zone to substantially eliminate the deposition of carbonaceous material therein.

2. A process for maintaining hydrocarbons under conditions of temperature and pressure which normally cause deposition of carbonaceous material, which comprises passing the hydrocarbons through an inner zone having an imperiorate hydrogen-permeable wall substantially free of aluminum and copper, maintaining hydrogen under sufficient pressure in an outer zone spaced from said inner zone by said hydrogen-permeable wall and having a substantially hydrogen-inn permeable outer wall to prevent passage of hydrogen therethrough to cause substantial flow'of hydrogen through said hydrogen-permeable wall of said inner zone into the hydrocarbons passing through said inner zone to substantially eliminate the deposition of carbonaceous material therein.

means,

tions which normally cause deposition of carbonaceous material in the heating and conveying comprising passing said hydrocarbons throughan inner zone having an imperforate hydrogen-permeable Wall and substantiallyfree of metals of the class consisting of copper and aluminum. under temperature and pressure conditions to'efiect cracking of the hydrocarbons, maintaining hydrogenunder sufficient pressure,

in an outer zone spaced from and surrounding said inner zone and having a lining substantially hydrogen-impermeable, said hydrogen being under suflicient pressure to cause the hydrogen to pass through said hydrogen-permeable wall and pass into said hydrocarbons being converted in said innerzone to substantially eliminate carbonaceous deposition therein. a

5. A process in accordance with claim 4 in which said outer zone is lined with a metal se- 3. A process in accordance with claim 2 in which said outer zone is lined with hydrogen-impermeable metal selected from the group consisting of aluminum and copper.

4. A process for converting petroleum hydrocarbons into relatively lower boiling and into relatively higher boiling constituents under condia substantially lected from the group consisting of aluminum and copper.

.6. Apparatus adapted for use with hydrocarbons heated to elevated temperatures including a tubular metallic vessel concentrically disposed within and spaced from an outer tubular jacket vessel, said inner metallic vessel having an imperforate hydrogen-permeable steel wall, means for maintaining hydrogen under sufficient pressure in the space between said'm'etallic vessel and said jacket ;vessel to effect passage of hydrogen through said permeable wall and into said metallic vessel to substantially eliminate carbonaceous deposition in said metallic vessel when heating hydrocarbons to elevated temperatures, said outer jacket vessel being lined with a metal selected from the class consisting of copper and aluminum to prevent passage of hydrogen therethrough.

a V FRANCIS R. RUSSELL. 

